SYNCHRONIZATION OF HUMAN FINGER MOVEMENTS - DELAYS AND SEX-DIFFERENCES WITH ISOTONIC ANTIPHASE MOTION

The interval between the operation of two Morse keys, or the moments a t which fingers touched or broke contact with electrical conductors, h as been measured, the subjects making the movements as synchronously a s possible. The data obtained deal with timings when two fingers flexe d or extended together ('in phase') and when one finger extended whils t the other flexed ('antiphase'). For antiphase movements of the index fingers with the conductors, flexion usually occurred before extensio n so there was 'overlap'. Statistically, this period was greater in wo men and unusually high values were found in one subject with mild cere bral palsy. Overlap was not found using the keys. Using conductors, th e timing of antiphase movements for the index and middle fingers of th e right and left hand showed overlap again. No significant relationshi ps were found with handedness. When the conductors were placed above t he fingers, and the contact was thus with the dorsum, extension took p lace before flexion; both fingers were extended for a while, with over lap occurring again. The significance of these findings for the unders tanding of motor control is discussed.